1. Field of the Invention
The present invention relates to a lubricating oil for flon refrigerant and more particularly to a lubricating oil containing, as a main component, polyglycol compound with high viscosity and small water content, which is suitable for a lubricant in refrigerators using a flon compound as a refrigerant and so forth.
2. Description of the Related Arts
Polyglycol compounds have heretofore been used as lubricating oils for refrigerators and so forth. When they are used in an open-type refrigerator and so forth, an evaporation loss is large because their viscosities are relatively low. Particularly when they are used in a high-speed and multi cylinder refrigerator, the amount of oil consumed is considerably large, and thus they are unsuitable for practical use. Moreover, when they are used in closed type and half-closed type refrigerators and so forth, they suffer from disadvantages in that the amount of oil recycled is increased and cooling performance is decreased. Conventional polyglycol compounds, when used as refrigerator oils and so forth, produce the copper plating phenomenon on the iron surface in refrigerators (this copper plating phenomenon means a phenomenon that copper eluted from copper pipes covers the iron surface) and thus have a danger of causing unsatisfactory working of vane, bearings and so forth.
The present inventors have studied to overcome the above defects of conventional polyglycol compounds and to develop a polyglycol compound having suitable properties as refrigerator oils and so forth. As a result, it has been found that water contained in polyglycol compounds is responsible for the above copper plating phenomenon. It has further been found that polyglycol compounds having a small water content and a high viscosity do not have a danger of causing the copper plating phenomenon and have good compatibility with various flon compounds to be used as refrigerants for refrigerators and so forth.